Humidity-Sensing Performance of TiO₂/RGO and α-Fe₂O₃/RGO Composites

This study investigates the humidity-sensing properties of two semiconductor metal oxide (SMO)-reduced graphene oxide (RGO) nanocomposites: TiO₂/RGO and α-Fe₂O₃/RGO, at room temperature. Both nanocomposites are synthesized via hydrothermal methods and coated onto printed circuit board (PCB) interdigital electrodes to construct humidity sensors. The surface morphology and crystallographic structure of the materials are characterized using field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD). The sensors are tested across a humidity range of 11%RH to 97%RH, and the impedance is measured over a frequency range of 1 Hz to 1 MHz. The results show that both TiO₂/RGO and α-Fe₂O₃/RGO exhibit favorable humidity-sensing performance at room temperature. The sensitivity and humidity hysteresis of TiO₂/RGO are 12.2 MΩ/%RH and 3.811%RH, respectively, while those of α-Fe₂O₃/RGO are 0.826 MΩ/%RH and 8.229%RH. The response and recovery times of TiO₂/RGO are 72 s and 99 s, respectively, while those of α-Fe₂O₃/RGO are 48 s and 54 s. Both sensors demonstrate good repeatability and stability. These findings suggest that SMO/RGO nanocomposites are promising materials for the development of low-cost, high-sensitivity, and stable humidity sensors.